1. Field of the Invention
The present invention relates generally to electronic equipment, and more particularly, to apparatus and methods for cooling electronic devices using plasma-driven gas flow.
2. Description of the Related Art
Electronic devices may generate significant heat during operation. High temperatures may reduce the lifespan of these devices, and, therefore, the generated heat may need to be dispersed to keep the operating temperature of the electronic devices within acceptable limits.
One commonly used cooling device is heat sink. Heat sinks may be coupled to electronic devices to absorb heat through the heat sink base and disperse the heat through their fins. Conventional methods to disperse the heat through the heat sink fins are natural convection and forced convection. Natural convection is to disperse the heat away from the surfaces of heat sink fins without the aid of external forced fluid pumping through heat sink fins. On the other hand, the forced convection cooling is to pump the fluid to flow through heat sink fins, such as the fans to blow the air through the heat sink fins, and therefore increase the heat transfer between fins and outside ambient.
With the increasing power density of electronic devices, the pitch or the distance between heat sink fins is becoming smaller, which means more surface area may be used to transport the heat away. However, when the pitch becomes very small, the pressure drop between inlet and outlet of the heat sink fins may become very high, which may result the difficulties to pump the fluid flowing through fins, and as a result, more powerful fans, which consume higher electricity may be needed for the cooling. The invention utilizes plasma-driven gas flow to conduct the convective heat transfer inside the heat sink fins and therefore will resolve these issues.
Another consideration of the cooling of the electronic devices is that, due to the size concern, the internal space allowed to put cooling fans and other cooling components, may be limited or not permitted. The invention utilizes the plasma-driven gas flow to generate the forced convective heat transfer inside the heat sink fins, and hence, is able to improve the heat transfer efficiency and to minimize the required space because the cooling components are assembled inside heat sink fins.
Another aspect of using the invention is to lower required power of the system fan power inside electronic devices. The plasma driven gas flow inside the heat sink fins will induce the local turbulence on the heat sink surface, and higher momentum of the fluid is obtained. Therefore, in this way, the system fan doesn't need to be very powerful in order to cool down heat source.
Plasma-driven gas flow has been used either to cool articles or to control and modify the fluid dynamics boundary layer on the wings surfaces of the aerodynamic vehicles. For example, U.S. Pat. No. 3,938,345 used the phenomenon of corona discharge, which is one type of plasma, to do the local cooling of an article. U.S. Pat. No. 4,210,847 designed an apparatus for generating an air jet for cooling application. U.S. Pat. No. 5,554,344 had a gas ionization device to do the cooling of zone producing chamber. U.S. Pat. No. 6,796,532 B2 used a plasma discharge to manipulate the boundary layer and the angular locations of its separation points in cross flow planes to control the symmetry or asymmetry of the vortex pattern.
However, none of the above patents are coupled to the heat sink, which is a fundamental apparatus for cooling electronic devices. Hence, what are needed are a method and an apparatus, to couple with heat sink fins to cool down electronic devices efficiently.